Sand-blasting machinery



Aug. 6, 1929. F. H. WOLEVER 1,723,112

I smn BLASTING MACHINERY Filed Feb. 4, 1924 5 Sheets-Sheet 1 "IA ZEN 7 08 W 0772271225 lv/r" Aug. 6, 1929. F. H. WOLEVER I AND BLASTING MACHINERY File d Feb. 4, 1924 5 Sheets-Sheet 2 Au 6, 1929.- F. H. WOLE VER 1,723,112

SAND BLASTING MACHINERY Filed Feb. 4, 1924 5 Sheets-Sheet 5 g- 1929. F. H. WOLEVER 1,723,112

SAND BLASTING MACHINERY Filed Feb. 4, 1924 5 Sheets-Sheet 4 qwavvrae IZ/fZZIZZfl 9/ 7 av Aug. 6, 1929. F. H. WOLEVER SAND BLASTING MACHINERY 5 Sheets-Sheet 5 Filed Feb. 4, 1924 Patented Aug. 6, 1929.

PATENT OFFICE.

FRANKLIN I-I. WOLEVER, OF CHICAGO, ILLINOIS.

SAND-BLAS'IING MACHINERY.

Application filed February 4, 1924. Serial No. 690,387.

This invention relates to improvements in sand blasting apparatus of that type that employs air at a high pressure as a medium of propelling sand or other abrasives at high velocity through a nozzle against metallic or any other substance to be treated.

Among the common faults with sand blast apparatus now in commercial use may be summed up the following; lack of positive sand flow, which causes intermittent volume variations of sand flow and varying velocities; lack of means for separating from the clean sand detritus, dust, and the like, Whereby same properly cleaned sand can be used over and over; inconveniently located manual controls remote from operative points, lack of proper provisions for ready access to vital parts of the operative mechanism to remove obstructions; lack of means for establishing sand flow after the sand blast has been shut off without experimentation with the sand and air valves, and inconvenient means for filling the sand tank after it has been emptied. In the operation of many types of machines, the operatives are required to wear dust masks in order to protect themselves against clouds of dust that arise from the sand blasting operation.

The purpose of the present invention is to overcome the above objectionsand to provide a sand blast apparatus having many other desirable features that will be more fully set out in the following description.

The foregoing brief statement of the construction and operation is made for the purpose of a survey before proceeding with a detailed description of the present embodiment of the invention and for the purpose of indicating the nomenclature herein observed to anticipate the general steps of the operation of the apparatus. It is to be understood that said statement is merely descriptive and is not intended to be limiting.

In the drawings:

Figure l is a side elevation of the machine and an end view of the car or work sup )ort.

Figure 2 is a front view of the mac ine with the car or work support in place.

Figure 8 is a horizontal section on line 33 of Figure 2.

Figure 4 is a vertical section on line 44 of Figure 3.

Figure 5 is an axial section through the sand tank and car.

Figure 6 is a cross section through the single stage sand jet on line 6-6 of Figure 5.

Figure 7 is a cross section through the sand jet receiving chamber at the bottom of the sand tank taken on line 77 of Figure 6.

Figure 8 is a cross section through the jet pump delivery on line 8-8 of Figure 4.

Figure 9 is a cross section through the jet pump to nozzle on lines 99, Figure 4. As shown in the drawings, A is the operators platform; B the shuttle car containing the blasting chambers B C the intake chamber of the sand cleaning and dust separator connected through an S-shaped trap E and conduit G at the converging outlet of said chamber to a cyclone or dust collector D and exhausing through an exhaust fan I) to the atmosphere. G is a sand pit below the separating chamber into which the sand falls through the grid-like bottom of said chamber. H is a sand tank to which clean sand is lifted from the sand pit below through the action of a jet pump I (Figures 1 and 2) which receive air under pressure through a pipe I from any suitable source and discharges the sand through a pipe I to a receiving chamber H above the clean sand chamber H when the sand is discharged into a sand chamber H. The sand is fed in the operation of the machine through the hopper bottom of the tank and through a sand measuring apparatus J (Figures 1 and 5) and thence through the nozzle hose K to the manually operated jet nozzle K by which the blasting sand is directed at suitable velocity and volume onto the Work in the sand blasting compartments B.

The car B is divided into the blasting compartments by partitions 15. Said compartments' are equal in width to the front end of the receiving end of the chamber C. The tracks 19 on which the car rests and rolls are provided with bumpers 20 to properly line the compartments relatively to the front open end of the chamber C. The work to be treated is supported on turntables 16 within the compartments, said turntables being mounted on the upper ends of vertical shafts 17. The turntables can be manually turned to present the work to the sand blast from the nozzle K when the latter are in the position shown in Figure 5. The work is preferably directly supported on removable wear plate 18 which can be replaced at small cost when worn by the sand blast.

The bottom2l of the chamber C is of grating or grid-likestructure to permit the clean sand to fall freely to the sand pit G below. The roof 22-of-the chamber .0 is solid from front to rear. At its front it has an upwardly flaring wall 231tern'1inating in a forwardly extending wall 24 which constitutes a hood toextendcver the Hasting compartments B and to furnish a large free-air intake to the chan iber C. Said hood is closed atits ends'by 'end'walls'2G to allord-propcr direction torthe incoming air. "Rubberor other-llexiblestrips' 2-8, fastened preferably to a suitable vertical part of the chamber C cooperate with the partitions 15 of the chamber-Cto close the openings'between the blasting compartments and the separator chamber C.

The'vertical side wallsofthe chamber C comprise outer-solid plates 30, which converge towards the rear end or the chamber, and-un ner louver'plates 'ill which are dis posed. atangles to the walls 30 and in planes parallel 'to each other. They relatively =ovei'lap'each other with their forward edges spaced urthest' from' the plates 30 to form the vertical louver-slits 32. Thes-and passes through said slits into the spaces between said louver-strips and the solid plates 30 and falls into the. pit below through slits 33in the'chamber floor igure The-S-shapedtrapE'atthe narrower discharge end .615 the chamber is located'over the rear endo'f' thesan'd pit' G. It is considerably restricted in width but about "the same vertical dept-h as'the chamber side walls. The side walls ofsaid' trap outlet are composed o'l s'olid and louver plates 3a, 35, respectively, and intervening bottom wall slits 36 tl1ereb'etween permit the sand caught between the louver and solid plates to flow-into the sandpit. The out-let leg of the indirect discharge passage thus formed communicates "throughout its height with dust and air discharge opening 37 (Figures '2 and 5) which communicates through the conduit -F and-its flaring outlet into the cyclone or dustseparator D of any suitable construction. if desired, the-floors of the trap may be providedwith gravity operated :trap doors 40, normally held close 1 .by springs l2 acting betwcen'arms 43- on said hinged trap doors and-rigid .J111Sll on the. adjacent structure (Figure The presence of saiddoors, when operating with relatively light-sand, to avoid drawing the sand out ofithe rear part of the sand =pitat the point wherewthe. velocity of :the airis high. The springs 42-can be so adjusted that thedoorswvi ll' be operated witha moderate weight of sand to dump sa'nd into the pit beneath, while normally serving to prevent current of -'air being established below and light particles therein on the'way the level of the chamber floor at the rear .thereof which would have a tendency to carry sand upwardly from the pit into the separator G. Moreover, these trap doors permit all the sand to be discharged from the separating chamber and its outlet when it is desired to entirely clean the sand from Ft-he machine, athe doors being adapted to be manually opened for such purpose. "The'brokenlinesSm Figures 3 and 5 1ndicate the manner in which the sand is deflected from the work V on the turntables '16, and thearrows in Figure 5 'in'dicate'the manner in which the air is drawn into and through the chamber and-thence to theidust collector D at high velocity-"to take up the dustand the lighter portions of "the sand and the particles brokenor-blasted ell the work. lVhile the air carries the fi hter n'iaterial' to the dust' collector, the heavier clean sand falls by gravity-to thesand-tank G througlmne openings inthe grid-like-bottom'and the openings 33*and 36 behind the "meets the-work. The blast alsov leaves the work in a. flaring'or"fan-dikeshape, as shown in Figure- The form cit-the separating chamber 'issuch that the sand and particles removed from the work by the blasting operation enters the front ot'the chamber C in a rather loose spraylike' form or with the paricles interspaced, so that the separating air drawn-intothe chamber-through the exhaust fan D an pass freely through and among the particles to separate and carry the lighter dust-and detritus from the relatively heavier particles ofisand orotheflblasting material. The air enters the front of the chamber throughout its height, as indicated by the arrows in- Figure 5,-and by reason of the/area of-the orifice thereat, the air passes into the chamber at relativelyslow Velocity and large volume; and its speed increases asdtpasses to the rean'restricted portion thereof. *By reason 01 theangle at'which the sand enters "the chamber the inwardly flowing; air has large and intimate contact with the inwardly projected massof said detritus and blasting clips and has an opportunity' to separate the lighter from the heavier particles thereof. This intermingling ofthe sand and air is also promoted by reason of the fact that some of 'thesalid strikcs'th'e louvcrplatcs at "angles-which again throws the'sand back towards the center of the chamber" for action thereon by the cleaning air. As the air approaches the rear restricted endof'the chambers its velocity increases so as to sustain the dustto the dust separator D through tlie trap E.

A greater portion of the sand will have been separated by gravity from the rearwardly moving mass before the mass reaches the trap, but'such particles of usable sand as are carried therebeyond will be separated by the louver plates 35, due to the centrifugal force of the sand particles as the mass is passing through the bends of the traps. Any-dust that may not be removed from the sand as it is deposited into the pit will be removed while the sand is being transferred from the pit, through the receiver H to the sand tank H, as hereinafter described. 7

In the operation of the type of the machine shown, the sand tank H first filled with sand. -When beginning the operation, the sand will be drawn from a source of sand supply outside the machine; After the machine is in operation, thesupply of sand will be that in the sand pit G, and it withdrawn therefrom through the action of the sand pump I (Figures 1, 5, 6 and 7). The said pump operates in a depression or trough l5 located at the bottom of the pit to receive all the sand from the pit by the natural flow line of the sand. The pump embraces a cylinder 46 (Figures 6 and 7) that communicates through a top opening 47 with the sand pit. To one end of said cylinder is connected the valve air pressure pipe 1 adapted to be connected with any suitable source of air under pressure. Said air pipe I discharges into a chamber 50, one wall 51 of which, within the casing 46, receives a jet nozzle 52 that lies in the axis of the said casing 46. The said wall 51 is provided below its axis with a plurality of openings 53 (Figure 6). The pipe 1 leads from the cylinder 46 in axial alignment with air jet nozzle 52. Therefore, when air under pressure is delivered to the chamber 50, its jets through the pipe 52 and the openings 53 and acts with an injector effect to force the sand througlithe pipe I -and raise and deliver it to the receiver H of the sand tank H. Y

Said pipe I leads tangentially into the side of the receiver, as shown in Figures 4 and S. The speed of the sand thereby is reduced and the sand is agitated as it enters the said receiver by impact against a series of radial projections 55 in the receiver of unequal effective heights, so that the sand is free to drop by gravity to the bottom of the receiver. The lighter particles are carried by air away from said. receiver back to the rear part of the chamber C to be carried to the collector D by means hereinafter described. a

The bottom of the receiver communicates with the tank H through an opening controlled by cone-shaped valve 56,- which con trols the flow of sand from the receiverto the tank. Said valve is vertically movable andseats upwardly against a ring 57, which,

as herein shown, is within the top of the tank H in axial alignment with the receiver and constitutes a continuation thereof. The ring fixed in any s iitable manner to the top wall/z- .of said tank, and its lower seating face is formed by an annular tapered body of resilient substance 58, such as" rubber, QOPlfOClUCG an air tight joint between the cone-shaped valve and said seat, for a purpose presently to appear. The said valve has a vertical stem which extends upwardly through a tubular guide carried by a spider within the receiver, and through a neck 61 having at its upper end a stem guide 62. An expansion spring (53 is interposeo between an upper face .on said neck and a shoulder 6% on the stem above the neck (formed by a threaded nut) and acts normally to hold the cone-like valve against its tapered seat.

A pipe 68 communicates with the upper end of said neck and discharges into the chamber C through its top wall 22 and serves to withdraw dust and light particles from the agiilted sand in said receiver. Thus the sand is subjected to a further cleaning action before it is discharged into the sand tank. WV hen the sand tank is to be filled, the jet pump is set in operation to raise the sand from the sand pit into the receiver H and the agitation of the sand as it enters the receiver, due to its impact against the wings 55, serves to reduce the speed of the sand and to cause the sand to drop by gravity and the (lust and lighter particles to be separated from the sand by the action ofthe draft of air through the pipe 66, due to. the low pressure in the chamber C, so that the sand is prepared inreadiness for entrance into the tank in a clean condition.

The seating strength of the spring 68 can be so regulated, as by the nut G l, that a given weight of sand overcomes it and opens the cone-like valve to allow the sand to flow by gravity into the tank below. The said spring (38, regulated as it is, cooperates with gravity to control the sand flow until the tank has been filled, and after the operation of the sand jet pump has been stopped, the said spring acts to hold the valve hard against its seat to provide a joint against the escape of air through the filling valve thus described during the sand blast operas tion.

An air vent is established from the tank while the tank is being filled through a vent pipe 68, the top of which opens near the top wall of the tank (Figure 4). Said vent pipe extends downwardly through the hoper bottom of the tank and is provided exterior to the tank with a branch (59 which discharges into the air. As herein shown, and for a purpose hereinafter be described, the said branch opens into a chamber 70, which can be fastened to the tank structure. Said'eh'amber is-proVided-at its bottom with an outlet" or -vent opening 71 which is-adapted to be open when-the sand tank is being filled, so as to -equalize'.the tank pressurewith the atmospherefbut said opening is adapted to be closed during the blastin operation to equalize the" tank pressure with the operating pressure. To this end, the 'ventor equalizing pipeextends beyond the outlet branch 69 to form an ektension' 70, for a purpose presentlyto appear.

Aft'erthe-sand tank is filled, the sand 'is discharged in measured 'quantities'itherefrom throughfithe nozzle K =underthe control of a suitable volume and pressureeentrol'nieans. 'One embodiment-of said control means is bestshown in Figure 4, and is made as follows:

designates a rotati-ve -'measuring-bo\i l which is axially below the discharge' nezzl'e 7G-ofthe sand tankat the-conical lower end at the tank. As-showiuthe nozzle is formed as an integralpart of the casing '77 of a measuring device; and thesmaller discharge of the said tank is' flanged touattacnn'ient to the upper -flattened end of said casing, with the tank discharge it in line witlrsaid nozzle. The "measuring bowl is fiXed to and rotateswitlr a vertical stub slriiit'78 which is rotatively mounted in a-bearing"79 that is carried by and is partly enclosed in a shell 80 of suitable form to protect said bearing from 'dust and sand. "The bearing is further protected at the point where the hub ofthebowl and the bearing members meet by a '-skirt"'80' "which is' arranged in overlapping relation -*to'th'e upper eonieal end of-said Shell 80. Fixed toehelowemnd of said shaft 78 is a'bev'eledgear wheef 81 that meshes Witha bGVGlGClPlHlOIlSQ. "Said pinion is fa'st to the inner endef a shaft 83 "that is mounted to lrota'te*in 'a bearing 84 v which is I carried b the casing' 77. The lower, tapered end 85 of the measuring de- Vice'ea-sing hasthe form of-a neekSG that eanbe made' 'integral with a fittingf87,' herein shown to be the ca-sing of a sand pump, through the medium "of whieh sand is d'eli-vere'd from' the measuring"device casing to the sand discharge tube and n'oz 'zleym's will hereinafter be described.

-The shaft 83 is fixed to =a worni geari"8 8 which meshes with worm 89' that is fixed to and rotates with the shaft of an air turbine' '90 (Figure 4). Said worm gears are enclosed in a sditablyzhapdsand proof casing to protect them from*sand= ancl du-stl 91' designates the casing of tlie' =ai1' turbine 90, one side of which casing is -open-to one branch 106 ofa pressurepipe92. *S'aid pipe 92 has a flanged axial cOnnectionat its lower end with the tapered receivin'ge-nd93 of the sand pump casing" 87,"there'heingm pressure chamber-94'torm'ed in said tapered formation "93 between the "adjacent end of the pipe -92 and a transv-er se swan or partition 95 in" said sand-pump casing 87.

Q Connected -to the end -o t thepipe 92' remote from t'he sandipump is a 'pipe' 97 for delivering air untler pressure to the pipe 92,

for -the double' purpose er furnishing air to operate the turbineand "for operating the sand pump -by whieht-he sand is f-orced through the"noz'zle' ?K'. Said pipe 97 "has cutoff and "controlling=valve' 98. The pipe 97 connnunieates with the 'pipe 92 through one lateral' branch of fitting99;another branchof the fitting being connected directly-to "the chnduit' 92. Said "fitting -is Valve controlled to shut off air pressureirom the pipe 97 *when the sand tank is being filled "and *When the-blasting operation is discontinued. A-valve 100 for this purpose is shown in Figure' l as being 'closed.

' Said valve 1 00 isa tapered-faced closure teengage a like-shaped seat-in-a diaphragm of the fitting 9.9. i-The stem 5101 er said Valve extends through a" 'stufling box at the top of the' fittingfancl is *connected by a coupling 102-With the-lowerend eta stem 103. The stem 1G3 ---'eiten'ds *upwardly througha-vchamb'er. 10st "madeof "upper and lower casing"nie-mbersand is conne'cte'd tn a diaphragm 105 wi hie'hyextends acrosssaid ehainber,=with the margin thereof "confined between the margins of the members of the two part oasing' in' aiknown manner. Said stem" 103 extends through a stuffing-box in the lower casing "member ';-'to 'maintain' air tight the lower} olia1nber ':104-= titsaid casing. Thestein is surrounded in its part between said diaphragm and'lthe top mem-ber of the casing "by a spi1'al-"-expa-nsion spring 107, the normal tendency+ot whieh is to elose said Yalve -1OO. llheu'ipper end of the stem lt )3,-above' the easing-r04, carries a "disc valve lQ3i to elose' the silt opening 71 in the equalizing ehaniber 'ftl before referred to. Loeated a v'ithi'n' the eontluit 92,-z,abre ast the air' 'tui-"bina is a partition 1O5'WVlllCl1 is'fr'ee at itsnpper and lower ends from the conduit wall and, in-"ellecfiprovides'two branch eond'uits i106, 1'07, the forme1- of;whic11 directs air to the yanes o f the turbine, and the latter of -whieh shuntsair from the turbine-"blades'and directs it to -the sand pump beneath 'the measuring mechanism. The said bra'n'ehes 196, 107 *are adapted to be separately controlledfto"vary' the v'olu'me of air passing therethreugh *by any suitable control er threttle' m ans s'ueh, for instance, as b 'meansrefstuds- 108, 109 that are th rea'd'ed "through the' opposite waills' of the conduit and are adapted at their inn'er ends to approach "and F re'e'ede" from the partition 105. s

The ysand 'pun'ip at'2tlie dis harge end of tlie 'volume 'measuring mechanism is general ly?siinilar *td'the sand pump whieh raises the sand from thepit'"td-the" receiving chamber of the sand tank. It embraces, in addition to the parts already described, a tube 110 (Figure 4) which lies axially within the casing 87 and is fixed at its rear end in a central opening in the partition 95. Said tube,

therefore, affords freepassage for air centrally through the pump chamber. The sand falls around the tube 110, as shown in Figures 4; and 9, in front of the partition 95. Said partition has in its lower part a plurality of openings 112. Air, under pressure, therefore, passes through said tube and through said openings 112 and acts with an aspirator effect to forcibly discharge the sand from the pump. casing through the nozzle. The nozzle has a restricted throat near its outer end afforded by a liner 11 1 made of a substance to resist wear. The said liner is flared at both ends and restricted between its ends so as to thereby impose a resistance to sand discharge andto increase the velocity of the sand projected from the nozzle.

Located at, and preferably'carried by the nozzle piece is a cutoff and control valve, designated as a whole by 115. As shown, its casing is provided with a collar 116 which is clamped about the hose K at the point where it laps over the nozzle piece K to thereby fasten the valve in place and to clamp the hose on the nozzle piece. The casing of said control valve is formed with three tubular. branches 117, 118, and 119. The branch 117 opens to the atmosphere. The branch 118 is connectedby a flexible hose 120 and a pipe 121 with the lower chamher 104 of the diaphragm casing 104. The branch 119 is connected by a flexible hose 122 and a pipe 123 with the main pressure pipe'97 just inside its valve 98. 12a is a plug that is rotatively seated in said casing and is provided with an actuating handle 125. Said plug is provided with two curved internal ports 126, 127, the ends of which are spaced angular distances apart equal to the angular spacin s of the ports in the branches of the casing, the spacings being 90 as herein shown.

In the adjustment of the parts shown in Figure 4 the lowerchamber 1041 of the diaphragm chamber 104 is open, through the port 127 in the plug, to atmosphere, so that the spring 107 is at this time active to close the valve and to open the sand tank vent 71. If the plug be turned 90 to the left from the position shown in Figure 4, the port 126 will connect the pressure pipe 97 with said lower chamber 10% of the diaphragm casing 104, whereby the pressure of said pipe 97 is effective to raise the diaphragm to open the valve 100 to admit air under pressure to the conduit 92, and thereby to the air turbine and the sand pump. Such air line pressure is also operative to close the valve disc 103 against the sand tank vent opening 71. These are the operative positions of the parts for sand blasting. 12S designates a branch which leads from the extension of the equalizing pipe 68 and communicates with the casing '77 enclosing the sand volume control mechanism, where pressure in said casing and the tank can be equalized during the sand blasting operation of the machine.

It is desirable that means he provided for limiting the effect of the sand head in the tank H, so as to'thereby reduce the feed velocity of the sand from said tank to the measuring device. This result can be of fected by arranging a cone-like shelf or diaphragm 130 within the sand tank above its discharge nozzle 76, and supporting it centrally in said tank by brackets 131 from the wall of the tank. This central support or shelf will modify the flow line of the sand in the manner indicated in said Figure l, and reduce the head pressure of the sand at the outlet nozzle to an extent represented by the area of said shelf.

In order that free access may be had to the outlet of the tank to remove clogging obstructions, a hood 132 is arranged below said shelf transversely across the conical lower end of the tank. The hood can be supported on opposite walls of the tapered portion of the tank. Atone end of said hood the tank wall is provided with a hand hole 133, covered by a suitable closure. Through the hand hole any suitable implement can be inserted into the restricted outflow of the tank to clear the outflow of any obstruction that may lodge there. The presence of said hood, to the extent that its side margins intercept the normal flow line from the margins of said shelf 130 further reduces the sand head pressure at the tank outlet).

The various parts of the apparatus may be supported in any suitable frame, such as is shown in the drawings, but, inasmuch as the particular character of the frame work will depend somewhat upon the installation, it has not been deemed essential to describe such work in detail.

The operation of the apparatus may be briefly stated as follows:

The workto be sand blasted is placed upon the turntables of one of the blasting co1npartmonts and the car or support is shifted to bring said compartment opposite to the chamber C. The motor 135 which drives the exhaust fan D is started, and the fan creates a high velocity and large volume of air flow through the front of the chain or C and rearwardly thereof and thence through trap E and conduit F to dust separator D, whence the air is'driven to atmosphere. This current of air is calculated to draw a volume of air through front of machine to equal at least feurtimes that blown through the sand blast nozzle, and this increased volume die placement will, carry all .fine dust. blasting detritusand tlie fine particles 01" sand that are no longer. useful .throughthe sand sepa-r rator and. into the dust collector. D. The sand thus-cleaned falls throughthe .gridsli'ke floor of said chamber and. is defiectedby the louver-like formation of the .side' walls" of the chamber and'trap to .the sand pit below, from whence it is raised by the said pump and is further cleaned in the receiver and deposited into the sand tank H.

To start sand blasting, the compressed air valve'98 is-turned' on, and the operator takes: the nozzle K piece in hisehand and turns the control valve plug, to a suitable stop (not shown) which: registers the port 126-with .theproper casing ports to connect the pressure pipe 97: to the chamber 104 beneath the diaphragm. The increased area of surface of the diaphragmover the: net surface of the valve 100 causes the valve 100 to lift and to therebycompress spring:107 and to also cause the disc valve 103 toseat against and: close the vent port 71 through which the tank pressure was: theretofore equalized withatmosphere. V The sandtank is noivv sealed off from the atmosphere and compressediair. now flows through valve 97 through the opening controlled-by the valve 100," and thence through-the branchpassages 106 and .10'Z-of the conduit292. A- portionof the-air is passed through the passage 106 over. the vanes of the turbine to-drive the same and another portion is-diverted through the branchpassage 107 to the chamber 94 at therea-r, of the. nozzle sand pump, and thence through nozzle hose'K and the nozzle KI. The air pressure built upin the chamber-"94 of the sand pump carries the sand delivered to. the pump casing through the hose and discharges it from nozzle K onto the Work W.

The small area of'the nozzle K as compared tothearea'of intake air passages 110, 112. builds up pressure in chambers 94 and 77, which is soon equalizeduin the tank by flow of air from saidchamber 77 throughsthe equalizing branch-128 andpipe 68 tothe tank (Figure 4). This pressure also serves to seat the sandfeed control cone-valve' 56 more tightly than bythe action of the spring 63 alone As soonas pressure isequalizedrin the tank, thecasingfi 7 andthe'saidpump, sand willbeginto flow into cup .7 5, which is being driven by, the turbine. 90 ata speeddue to the control of the branch 106 which delivers air to said turbine. Rotationof. the bowl acts to centrifugally. throwthe sand delivered. thereto outwardly and cause it to floWto the restrictedoutlet 0r. passage ofthe casing .77,' from.whence-:.it. is forced to-the discharge or. blastin i nozzle KI. Obviously the more. rapidly thebowlisrotated the reater. will'be the volume of sandfdelivered down through the nozzle fit ofthe sancttank;

The control: of. as. rvpfazcli of "this. bowl;

area-1 12 through controlling: its-driving, turbine by. the actionot the valve 108, or equivalent throttling,means,.has theveflect to vary the volume of sand'deliveredlto the sand pump 'belowdn-a giventimeh Likewisathe operation offthe-valvevl09 or an equivalent control-for the highpressurebranch 107 serves to control the velocity at whichlairis-deliv cred. to'the chamber 9ofthe. sand pump. Withthese controls itnvill be. obvious that the. sand volume and. velocity discharge at the nozzle-cambe accurately varied to suit different. kinds. of. work. lVit-h a constant feed pressurein the pip.e,97.it'will be obvious that the. valves 108 and 109v will permit a considerable range of-"relative volume and velocityof air delivered to the-turbine and to the'punlp throughthe branches.106,.107, with a. corresponding variation, as stated, withrespect to. thevolume and velocity of the sand di scharged'from the nozzle. K. onto the work l/Vhen sand. fromthetankH has been exhauSted,,the valve 115 at the:nozzle K. is turned by its handle 125,.soas toclose communication from the feed or pressurerpipe 97 toithe conduit 92 and'to the pressurechamber 104. of the: diaphragmcasing andto establish communication. from said. diaphragm chamber. 104K to the atmosphere. The spring 107 then becomes activev on. the diaphragm to close the. valve and1to-open the equalizing port. 71 so as to equalizethepressurein the tank with the e atmosphere. Thereafter thesand pump-.1. is-set inoperation toiagain' charge thesand tank-LH,- after which the hand valve115 isadjusted to openthejvalve 100 to connect the feed pressure pipe to the conduit; 92, whereupon the machine is again in position. for sand blasting operation.

, Ifclaimas my invention:

1.v In a sandblasting apparatus, an open front separating chamber, with moans to 1nduce a. rearward How of: air therethrough to andthrough a. rear outlet, asupportior the work-in front ofsaid chamber, :confinin means for directing sand and chips deflected from the work intmsaidchamber and for directing; air in large volume through the sand so. deflected. into said, chamber, and a sand pit below said chamber, the sidewalls of "said chamber, converging toward the ch amber outlet. and formed with louver like slits,vbacked by solid portions, and the bot tom of said'chamber being. of grate formation to direct sand falling; thereon to the. said sand 'pit;.

2. In a sand blasting apparatus,a separating chamber openat its front to receive blasting sand and chips .defiected from. the Work beingblasted, and having a large air receiving mouthopening over said support, the side Walls of said chamber: converging towards the rear ofthe chamber and teeee with vertically leu'ver lilte lit backed by solid wall portions, the floor of said chamber being of grid formation and provided back of the louver-like slits with sand discharge slits, and means connected to the rear end of said chamber to induce a flow of air through its open front and rearwardly through the chamber.

3. In a sand blasting apparatus, a separating chamber open at its front to receive blasting sand and chips deflected from the work being blasted, the side walls of said chamber converging towards the rear of the chamber and formed with vertically disposed louverlike slits backed by solid wall portions, the floor of said chamber being of grid construction and provided back of the louver-like slit-s with sand discharge slits, and means at the rear end of said chamber to induce a flow of air through its open front and rearwardly through the chamber, the rear end of said chamber having the form of an indirect trap, the walls of which are also formed with vertical louver-like slits and imperforate wall portion backing the same and with sand discharge slits in the floor of the trap walls back of said louver-like slits.

1-. In a sand blasting apparatus, a separating chamber open at its front to receive blasting sand and chips deflected from the work, the sides of said chamber converging towards the rear of the chamber, the floor of said chamber being partly of grid formation, means connected to the rear end of the chamber to induce a flow of air through its open front and rearwardly through the chamber, a sand pit below said chamber and a trap door in said floor near the chamber outlet opening into said sand pit.

5. In a sand blasting apparatus, an open front separating chamber, the side walls of which are slitted and converge toward a rear outlet, and the bottom wall of which is of grid formation, a suction fan connected to said outlet to induce a flow therethrough, a work support in front of said open end of the chamber, and confining and guiding means for directing sand deflected from the work and air into said chamber in a manner to draw the air through the sand to carry rearwardly the lighter particles of the sand stream while allowing the heavier particles to fall to the bottom of the chamber.

6. In a sand blasting apparatus, an open front separating chamber, means to induce rearward air flow therethrough, and a movable work support having two blasting compartments adapted by movement of said support to register one compartment with the front opening of said chamber and to locate the other compartment in work unloading and loadingposition, said compartments bebonnded at the sides by upri ht walls of substantial height, said eing so i that ti: at the s. ct mmpartment register with the sides of said chamber when such compartment is in registration with the chamber.

7. In a sand blasting apparatus, an open front separating chamber, means to induce a rearward flow of air therethrough, a wheeled work support provided with two front and rear opening blasting compartments, a track on which said support rests and rolls, whereby either of said compartments may be brought into register with the front opening of said chamber, with the other compartment in unloading and loading position, and stops at the ends of the track to arrest said support with either of its compartments in register with said'front opening of the separating chamber, said compartments being bounded at the sides by upright walls of substantial height, said walls being so spaced that those at the sides of each compartment register with the sides of said chamber when such compartment is in registration with the chamber.

8. In a sand blasting apparatus, an open front separating chamber, means to induce rearward air flow therethrough, a movable work support having two blasting compartments adapted by movement of said support to register one compartment with the open front of said chamber and to locate the other compartment in work unloading and loading position, and means associated with the compartment structure and the chamber structure at the sides of the open front thereof to guide deflected blasting material and chips from said compartments to said chamber and to provide dust proof joints between said structures, said compartments being bounded at the sides by upright walls of substantial height, said walls being so spaced that those at the sides of each compartment register with the sides of said chamber when such compartment is in registration with the chamber.

9. In a sand blasting apparatus, an open front separating chamber, means to induce rearward air flow therethrough, a movable work support having two blasting compartments adapted by movement of said sup port to register one con'ip-artment with the open front of said chamber and to locate the other compartment in work unloading and loading position, said compartments be ing bounded by upright walls and packing means on the chamber structure at the sides of the front opening thereof adapted to en gage said compartment walls.

10. A sand blasting apparatus comprising means to jet a flow of sand against the work and deflect it therefrom, means to clean the sand deflected from the work, a sand pit to receive the clean sand, closed sand tank to the disel'iarge end which the sand jet 1 connected, receiv at i ,n my iii, means to tfl bM-(ffii' sahdi'romsaid pit ;to said receiver, deflect 111g blades .111 said :IGGGlVGI against ,WhlCll the sand transierredfrom thesandipitio the receiver impinges ,by-impact, a suction 5 pipe connected to-theupper part of said 1e-; celver, gandrimeans at; ,the vlower. part of vthe receiver 300 transfer clean; sand therefrom 4 to;

said frank, c

In witness as my -.inventicn,;1 hereunto append my signature this lthday of January; 192%. FRANKLIN-l1. \VOLEVER.

whereof. I clailnthe foregoing 

